Changes between Version 25 and Version 26 of OMI_observation_modules

Timestamp:

Dec 9, 2021, 3:48:23 PM (2 years ago)

Author:

lnerger

Comment:

--

OMI_observation_modules

@@ -171 +171 @@
    - `srange`: The support radius of the localization
 
+== Additional routines for 3D-Var ==
+
+For the 3D-Var methods added with PDAF V2.0 two more routines are required in the observation module.
+
+=== `obs_op_lin_TYPE` ===
+
+This routine applies the linearized observation operator to a state vector. It returns the observed state vector to PDAF. The routine is used only by the 3D-Var methods.
+
+'''Note:''' A separate routine for `obs_op_lin_TYPE` is only required if the full observation operator in `obs_op_TYPE` is nonlinear. If `obs_op_TYPE` is linear, one can just insert calls to this operator in the routine `obs_op_lin_pdafomi` in `callback_obs_pdafomi.F90`.
+
+PDAF-OMI provides several linear observation operators. For example the observation operator for observations that are grid point values is called as:
+{{{
+    CALL PDAFomi_obs_op_gridpoint(thisobs, state_p, ostate)
+}}}
+
+Here, `state_p` is the state vector and `ostate` is the observed state vector.
+
+For more information on the available observation operators and on how to implement your own observation operator see the [wiki:OMI_observation_operators documentation of observation operators for OMI].
+
+=== `obs_op_adj_TYPE` ===
+
+This routine applies the adjoint observation operator to an observation vector. It returns the state vector to PDAF. The routine is used only by the 3D-Var methods.
+
+PDAF-OMI provides consistent pairs of linear observation operators. For example the adjoint observation operator for observations that are grid point values is called as:
+{{{
+    CALL PDAFomi_obs_op_adj_gridpoint(thisobs, ostate, state_p)
+}}}
+
+Here, `ostate` is the observation vector and `state_p` is the state vector.
+
+For more information on the available observation operators and on how to implement your own observation operator see the [wiki:OMI_observation_operators documentation of observation operators for OMI].
+
+
 == Implementing a new observation type ==